The present invention relates to a compensating brake fluid reservoir, in particular for a vehicular hydraulic brake system, comprising a brake fluid level alarm device including a float chamber surrounding a float. The float chamber is defined by a bottom element and a tubular body, the tubular body being suspended from a threaded upper open end of the reservoir and the end of the tubular body immersed in the brake fluid having an opening.
In a known compensating reservoir of this type, for instance, as disclosed in German Patent DE-OS No. 1,630,037, the tubular body centers the float in order to avoid a tilting of the float within its guideway. The reservoir is attached to a master brake cylinder by means of a stud bolt arranged in the outlet socket, by means of a bottom element, and by means of a plate-type disc having passages. In this arrangement, the position of the bottom element serving to center the tubular body must be concentric with respect of the thread of the upper open end of the reservoir in order to ensure that, when screwing the tubular body in, the lower end thereof will embrace the bottom element without play. When screwing in the tubular body, it may happen that the tubular body will not enclose the bottom element, but rather rest on the bottom element and be moved out of place in such a manner that the float will be jammed in the tubular body. Thus, the fluid level indicating device will no longer be able to operate. The way of attaching the compensating reservoir at a master brake cylinder is complicated and expensive and does not permit universal application.
Further, from the German Patent DE-OS No. 2,720,596 it is known that the tubular body arranged in the compensating reservoir also performs the function of a damping chamber. In this arrangement, a primary function of the tubular body is to prevent the float from dancing up and down in case of vibrations acting on the compensating reservoir and, thus, causing faulty alarms. Another function of the tubular body is to center the float in its direction of motion in order to prevent the float from being jammed in its guideway.